2 Speedometers?

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mkfrd

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General question. Not sure why my LTC Cartier has two speedometers, digitaI would and analog. I would much rather have a tach, in place of the dial speedo. Which brings a question. Why don't the two match speeds? Is this typical, or do I have an issue?
 

All2kool

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Mine matched. How off are yours?

You can disable the digital one if it bothers you. Can't remember exactly how to do that but when I first got my 2004 Signature, the digital speedometer was not active. I activated it so there must be a way to deactivate it.
 
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mkfrd

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Mine matched. How off are yours?

You can disable the digital one if it bothers you. Can't remember exactly how to do that but when I first got my 2004 Signature, the digital speedometer was not active. I activated it so there must be a way to deactivate it.
Under about 35, they match. The faster I go, they can be 15mph off. According to my GPS, the digital is correct.
 

dave42

Senior Member
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Leander, TX C.K.U.
Well, that sounds way off. You didn't just leave out a decimal point and mean 1.5 mph difference? That would have been more reasonable! My digital and analog differ by maybe 1 mph at times. Both are about 1 mph higher than the GPS.
 
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Well, that sounds way off. You didn't just leave out a decimal point and mean 1.5 mph difference? That would have been more reasonable! My digital and analog differ by maybe 1 mph at times. Both are about 1 mph higher than the GPS.
Mine is off also. Digital is accurate. Analogue is about 2 mph high.
 
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mkfrd

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Well, that sounds way off. You didn't just leave out a decimal point and mean 1.5 mph difference? That would have been more reasonable! My digital and analog differ by maybe 1 mph at times. Both are about 1 mph higher than the GPS.
Nope. At 65, my analog reads 50.
 

Town

Senior Member
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Ottawa Ontario Canada
Is this for your 2003 model? The road speed info is provided by the ABS module and processed by the PCM and displayed by the Instrument Cluster module. Same info for both speedometers. I will see if I can find any info on that problem.
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Town

Senior Member
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Ottawa Ontario Canada
I cannot find a symptom for a speedometer that is 15 mph slow at 65 mph. The attached diagnostic suggests looking for DTC in the PCM after running some self tests. If there are no codes then a scanner is hooked up to the Instrument Cluster module and the speedometer mode entered and commanded to run speeds from 0 to 120 mph and back to 0. If OK then look for problems with the PCM and if not OK to check for damaged or corroded or pushed out pins etc on the Instrument Cluster connector.

The tests with the PCM are to remove all the connectors and check for corrosion, damaged or pushed out pins. Since the digital display of speed is correct then the problem is not with the PCM.

Looks like your problem is an Instrument cluster DTC shown by PCM or the instrument cluster itself electronic circuits problem. The possible pin connection problem is unlikely since digital speedometer works properly. I don't know how to diagnose the instrument Cluster circuits or how to repair. A dealer diagnosis and correction may be needed.

Good luck.
 

Attachments

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mkfrd

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I cannot find a symptom for a speedometer that is 15 mph slow at 65 mph. The attached diagnostic suggests looking for DTC in the PCM after running some self tests. If there are no codes then a scanner is hooked up to the Instrument Cluster module and the speedometer mode entered and commanded to run speeds from 0 to 120 mph and back to 0. If OK then look for problems with the PCM and if not OK to check for damaged or corroded or pushed out pins etc on the Instrument Cluster connector.

The tests with the PCM are to remove all the connectors and check for corrosion, damaged or pushed out pins. Since the digital display of speed is correct then the problem is not with the PCM.

Looks like your problem is an Instrument cluster DTC shown by PCM or the instrument cluster itself electronic circuits problem. The possible pin connection problem is unlikely since digital speedometer works properly. I don't know how to diagnose the instrument Cluster circuits or how to repair. A dealer diagnosis and correction may be needed.

Good luck.
That's kind of what I'm thinking. Thanks for the reply.
 

04TC

Junior Member
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Tampa, FL
Mine matched. How off are yours?

You can disable the digital one if it bothers you. Can't remember exactly how to do that but when I first got my 2004 Signature, the digital speedometer was not active. I activated it so there must be a way to deactivate it.
To turn the digital speedometer on or off in a 2004 signature you press the instrument cluster "SELECT" button until the LCD display shows "SPEED" and then press the "RESET" button while "SPEED" is showing. (Same menu as trip meter, mpg, distance to empty, etc.) Other years may be different.
 
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Analog speedometers, even if they aren't as analog as they used to be, are still somewhat mechanical and more prone to error than digital.
When I had my cluster apart to replace the transformer to cure the blinking right display bank, I semi-assembled it and physically adjusted the needle
position to match the digital at 55mph or so. It's still, as is fairly normal in my experience, a little low at way lower speeds and a little high at much higher speeds but only by a few mph. That said, 15 is quite excessive though, either it was assembled wrong, it's been apart and re-assembled wrong, or it's just failing. At 0mph where does the needle sit? Those clusters are relatively easy to service with replacement second hand parts fwiw.

I hardly ever look at my analog one to be honest(but it would bother me too if it was dramatically off), I've always been of the opinion that digital clusters were sometimes amusing and interesting but give me a nice full analog set
any day, but my eye invariably goes to the digital one in this car.
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Thread starter #13
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Analog speedometers, even if they aren't as analog as they used to be, are still somewhat mechanical and more prone to error than digital.
When I had my cluster apart to replace the transformer to cure the blinking right display bank, I semi-assembled it and physically adjusted the needle
position to match the digital at 55mph or so. It's still, as is fairly normal in my experience, a little low at way lower speeds and a little high at much higher speeds but only by a few mph. That said, 15 is quite excessive though, either it was assembled wrong, it's been apart and re-assembled wrong, or it's just failing. At 0mph where does the needle sit? Those clusters are relatively easy to service with replacement second hand parts fwiw.

I hardly ever look at my analog one to be honest(but it would bother me too if it was dramatically off), I've always been of the opinion that digital clusters were sometimes amusing and interesting but give me a nice full analog set
any day, but my eye invariably goes to the digital one in this car.
They both read zero when sitting. My left bank occasionally blinks. I think I might have an electrical nightmare with this car.
 
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Those clusters aren't trouble free after some age, there is a swift trade done in repairing instrument clusters for nearly all cars. If the needle sits ON the stop pin it's actually a bit below zero, I can't recall where mine sits after I set it to match 55 on the digital but it likely isn't dead on zero. If for some reason at some point in that cars life the speedo needle has been removed and reinstalled incorrectly, it could still sit on the stop at rest and be off further up the gauge since it can't rest much below zero. I kind of doubt that's your issues but it's possible. I'd buy a good used cluster and go from there if you're comfortable taking one apart, or send yours off to be repaired if not.
 
I, too, prefer to look at the digital speedo. On my '95 of course there was no analog at all, but I definitely got used to seeing the digital speed in the center of the display. I don't like having to look to the left for it on my '03. I wouldn't necessarily need a tach, but the later cars that added the tach and put the digital back in the center is one feature I wish mine had.
 
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I think the later one had a much smaller digital readout, I think it was them anyway.
I wanted a tach too but after looking at them a while that setup looked kinda goofy in a Town Car to me.
Can't have everything I guess.
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